This protocol permits the evaluation and treatment of subjects with hereditary and acquired hemolytic diseases, to facilitate understanding of pathogenesis and natural history vaso-occlusive painful crisis and pulmonary complications of sickle cell disease and related cardiopulmonary complications of other hereditary, acquired and iatrogenic hemolytic disorders. Patients are evaluated with a medical history and physical examination and routine laboratory studies are obtained as needed to assess diagnosis, disease activity, and disease, and disease complications and to monitor for treatment-related responses and toxicities. Blood is obtained, with subject?s consent, for research studies evaluating gene/protein expression and to evaluate the role of vasodilators, vasoconstrictors, inflammatory and redox stress mediators in this population. Patients identified with pulmonary hypertension have the option to undergo invasive hemodynamic evaluation and treatment with Food and Drug Administration (FDA) approved drugs, according to current standards of medical practice, with signed informed consent for all offered procedures. Patients eligible for other research protocols are offered the opportunity to participate in these studies by signed informed consent. Apart from such protocols, any medical care recommended or provided to the patients are consistent with routine standards of practice and are provided in consultation with the patient?s referring physician. The study provides a means to evaluate and treat patients, and to generate hypotheses and protocols based on this clinical experience in sickle cell disease and in other acquired or inherited hemolytic anemias. This study began enrolling subjects in April 2004 and we currently have enrolled 38 patients.